The subject matter described herein relates generally to methods and systems for wind turbines, and more particularly, to methods and systems for a modular rotor blade hub for wind turbines.
At least some known wind turbines include a tower and a nacelle mounted on the tower. A rotor is rotatably mounted to the nacelle and is coupled to a generator by a shaft. A plurality of blades extend from the rotor. The blades are oriented such that wind passing over the blades turns the rotor and rotates the shaft, thereby driving the generator to generate electricity.
The development of wind turbines constantly aims for higher power outputs, which leads to increasing size of the installations. In recent years, the size of the largest available turbines on the market has doubled every 5 years, a trend which seems to be becoming more prevalent. One of the reasons for this is the goal of lowering the cost of electricity (in cent per kWh), while at the same time increasing the energy capture (yearly average power output, AEP). Accordingly, it is a general objective to increase both the energy conversion at a given rotor size and to increase the rotor size itself, which leads to a higher average power output.
However, increasing rotor size also means a general increase in machinery and nacelle size, which leads to higher total masses, and also to an increasing mass of the rotor blades and the hub. Accordingly, increasingly heavy components result in the fact that single pitch bearings or yaw bearings reach their tolerable bending moments or thrust components. Hence, larger wind turbine sizes also mean greater dynamic loading and consequently require constructional measures to account for the higher loads. One measure to meet these requirements is to adapt the dimensions of parts, for instance the hub. Consequently, the hub tends to increase in size and weight, which is not desirable in terms of transportability, and the handling at the construction site.
Accordingly, there is a desire for a hub for a wind turbine which delivers improved stability and load bearing capacities for larger wind turbines, while at the same time the effort for transportation shall be reduced and the handling of the hub during construction of the turbine shall be improved.